Merge "Clear preferred top focusable root task" into sc-dev am: ba19c63b am:...

Merge "Clear preferred top focusable root task" into sc-dev am: ba19c63b am: 81a44019 am: dd9289ae

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/14514106

Change-Id: I8e0cde793ff1e0c3a6ff8808d7bdb83f8c8c63b3